Function run_shell 

pub async fn run_shell<I, O>(
    input: I,
    output: O,
    endpoint: &str,
    shell_jwe: &str,
    resize: Receiver<(u16, u16)>,
) -> Result<ShellOutcome, Error>
where
    I: AsyncRead + Unpin,
    O: AsyncWrite + Unpin,

Opens the shell and relays raw terminal bytes until one side ends the session.

input/output are any async byte streams, so the CLI drives this with the process’s raw-mode stdin/stdout and a test drives it with pipes. resize is a watch channel of (cols, rows): the value at entry is sent immediately — the guest reports 0 0 until something does — and every change afterwards becomes one validated control frame.

Output is flushed per frame, because the reader on the other side of output is a human watching a prompt: a byte held in a buffer is a keystroke that appears to have been eaten.